Ships are 'she,' people have motherlands and fatherlands, but what about a picture of a baby with the number '1' on it? What about a nice beef stew? Or a chair? Strangely, we tend to assign genders to all of them in a fairly predictable way.

Many languages assign masculine and feminine genders to everyday objects. These nouns have special articles attached to them that signal their gender. For example, French gives 'masculine' objects the article 'le,' while 'feminine' objects are preceded by 'la.' Those people learning these languages are often baffled by the arbitrary shifts between male and female. A plate may be male while a saucer is female, and a fork is female while a teaspoon is male. The shifts don't follow any pattern.

This lack of pattern doesn't mean there's a lack of consensus. Even in English, in which every object is nice and neutral, the majority of people assign gender to objects according to certain factors. Not all of those factors are comfortable to consider. Foreign names tagged with the number '1' are more likely to be considered male by people participating in a study. So are baby pictures. Meanwhile, babies and names tagged with the number '2' are more likely to be considered female. Divorced from pictures or words entirely, overall study participants rated the number '1' and all odd numbers as male, while '2' and even numbers are rated as female. Why? Is it a straight-up ranking? Is it an unconscious pairing instinct? Are women more easily divisible or men just plain odd?

Our assignment of gender spills over onto objects as well. Food items like salads and dairy products are coded female by study participants, while meat dishes are male. Rounded objects are female while sharp ones are male. We don't need explicit gender to apply our assumptions about gender to the world around us. We do it implicitly, every day, even when we don't need to.